A technique of installing a diesel particulate filter and the like in an exhaust path of a diesel engine as an exhaust gas purifying device (post-processing device), and performing purifying processing on the exhaust gas discharged from the diesel engine through the diesel particulate filter and the like is known. The aforementioned diesel particulate filter is abbreviated to a “DPF” hereinafter.
Construction machinery includes a diesel engine and a hydraulic pump, and the diesel engine outputs power to drive the hydraulic pump, and the hydraulic pump discharges hydraulic oil so as to operate a hydraulic circuit.
Exhaust gas is unavoidably discharged while driving the diesel engine, and the exhaust gas contains nitrogen oxide (NOx), of which the nitrogen oxide causes pollution by negatively affecting the atmospheric environment. In order to solve the problem, the aforementioned DPF is used. The DPF is installed inside an exhaust gas muffler in typical construction machinery.
In the meantime, soot of particulate generated by incomplete combustion of an engine is accumulated in the DPF. The soot degrades performance of the DPF and increases back pressure of the exhaust gas muffler, which degrades performance of the engine. Accordingly, in order to maintain performance of the DPF and the engine, soot needs to be removed.
When a temperature of exhaust gas is high, soot is naturally combusted and removed. The removal of the soot is referred to as a natural regeneration. However, when the aforementioned natural regeneration is not properly performed at an appropriate time, the soot eventually needs to be forcibly removed, and such a removal of the soot is referred to as active regeneration.
For the active regeneration, a method of forcibly increasing a temperature of exhaust gas by forcibly increasing an output of an engine or forcibly combusting exhaust gas at a temperature for removing soot by injecting fuel to exhaust gas of which a temperature is forcibly increased.
The active regeneration may be scheduled by a program, however, the active regeneration according to the schedule by the program is not efficient.
The problem of the active regeneration by the program in the related art will be described in more detail.
It is necessary to differently set an active regeneration time for each type of construction machinery, and it is necessary to differently set an active regeneration time for each work environment in which construction machinery is operated.
Further, there are various controls, such as an engine operation time control, a driving distance control, a fuel usage quantity control, a DPF differential pressure sensor control, and a simulating control, and the active regeneration is scheduled for each control, and a schedule of advent active regeneration among several active regeneration schedules is selected and the corresponding active regeneration is performed in an electronic control unit (ECU).
That is, in the related art, without considering the quantity of soot after performing the active regeneration, the active regeneration fails due to a shortage in the quantity of load or the quantity of temperature during performance of the regeneration or the active regeneration is performed only at a set time even after a starting is off, such that a problem of causing damage to the DPF is generated.
Accordingly, a method of controlling the active regeneration of the DPF considering fuel efficiency while maintaining performance of the DPF and performance of the engine is demanded.